1. Field of the Invention
The invention relates to a feed pump with a driven impeller rotating in a pump casing, with at least one ring of blade chambers which is arranged on one end face of the impeller, with a feed channel located opposite the ring of blade chambers and arranged in the wall of the pump casing and with moving blades laterally delimiting the blade chambers.
2. Background of the Invention
Feed pumps of this type are known as peripheral or side channel pumps and are often used in fuel feed units of motor vehicles. An electric motor arranged in the pump casing drives, via a shaft, the impeller which is located in the pump chamber. A feed channel located opposite the blade chambers is arranged in the wall of the pump chamber. As a result of the rotation of the impeller, fuel is sucked in through an intake orifice arranged in the pump chamber and is fed to an outlet orifice by means of the blade chambers and the feed channel. The liquid to be fed enters the blade chambers in the radially inner region of these due to centrifugal forces and emerges again in the radially outer region of the blade chambers. Since the blade chambers and the feed channel are at least approximately closed, a circulating flow is formed in the liquid.
In order to improve the efficiency of these feed pumps, numerous geometric designs are known for the inlet region into the pump chamber, for the feed channel and for the impeller. The configuration of the blade chambers and of the feed channel, in particular the cross section, is of great importance in the design of the impeller. In this case, impellers with mutually opposite rings of blade chambers have proved particularly suitable.
In order to improve the circulating flow between the feed channel and the blade chambers, it is known, furthermore, to arrange the moving blades of opposite blade chambers in a V-shaped manner in relation to one another, so that the moving blades are open forward in the direction of rotation. This arrangement of the moving blades allows energy to be transmitted to the flow more effectively. At the same time, turbulences occurring on the rear side of the moving blades are reduced. Impellers of this type therefore have improved efficiency, as compared with impellers, the moving blades of which are arranged perpendicularly to the end face.
Impellers of feed pumps are also known, the moving blades of which are twisted in the radially outer region very sharply in relation to the radially inner region. In addition to the complicated manufacture of impellers of this type, the flow behavior in the blade chambers may be adversely influenced on account of the pronounced angle difference between the inner and the outer blade regions.